A person who has no hobbies but to do nothing with their spare time souly to sabatage other peoples activities and/or fun, many times using reverse psychology to bring him,her, or them, down to the instigator's (hobby nazi's) level of wasting spare time purposly to " bore and screw them out of the other persons usual spare-time activities"

If other people can go about participating in their hobbys in which the hobby nazi cannot do, he/she will try to bring you down with them, into doing nothing.